Sony Ericsson's first Windows Mobile smartphone, the Xperia X1, will arrive on the O2 network next month.
Sony Ericsson Xperia 1
Sony Ericsson's Xperia X1: remember, remember the ??? of November...
Although several availability dates have already been suggested X1, SE said early in early September that the phone would …

Already on sale in Sweden

Expansys say 27th October for them

From the comments Expansys have given, it looks like all the UK telcoes who are going to take on the X1 (Vodafone, O2, and T-Mobile) have rejected the phone, resulting in all stock being sent back to Sweden for a new version of the firmware.